Adsorption and Permeation

We have covered a body of material in this chapter that deals with movement of mass along gradients and between phases. We have examined the commonalities and differences between linear driving forces, net rates of adsorption, and permeation. Each has the common feature that reaction is not involved but does involve transport between apparently well-defined regions. We move now to chemically reactive systems in anticipation of eventually analyzing problems that involve mass transfer and reaction. 

Effect of gas pressure on adsorption and surface permeation processes. In order to understand the nature of this gas evolution following a previous charge of the furnace tube with gases, it is necessary to study the extent of adsorption and permeation of the gases into the tube material as a function of the pressure with the intermediate chamber evacuated. The extent of these processes is measured by apparent leak rate measurement 10 minutes after evacuation of the gas. 

DYNAMICS OF ZEOLITE PORES AND CONSEQUENCES FOR ADSORPTION AND PERMEATION... 

In particular in the case of naphthalene, the pore apertures deform from a circular to a highly ellipsoidal shape upon adsorption and permeation. Next, this peristaltic behavior of the pore deformation is completed by the partial return of the ellipsoidal into a more circular aperture as the molecule is stabilized between the apertures. 

Dynamics of zeolite pores and consequences for adsorption and permeation Small pore zeolites Medium pore zeolites... 

The objective of this chapter is to present the fundamental theories of adsorption followed by the description and discussion of experimental techniques for the measurements of adsorption isotherms and for the determination of surface area and pore size distribution. The adsorption of gases on microporous membranes and the inter-relation between adsorption and permeation are then discussed. The adsorption in liquid phase is briefly presented. The chapter concludes with a brief summary. 

There are relatively few studies dealing with adsorption on microporous inorganic membranes. Except the work by Ma and his co-workers and Burggraaf and his co-workers, few studies on the interrelation between adsorption and permeation have been reported. The extremely thin membrane layer on a relatively thick membrane support makes the adsorption measurement rather difficult. Neither gravimetric nor volumetric technique will provide sufficient accuracy for the measurement due to the extremely small fraction of the membrane layer in a supported membrane. Nevertheless, adsorption measurements can give important information on pore sizes and permeation mechanisms in microporous membranes. This section will examine the adsorption of gases on microporous membranes and of liquids on mesoporous and macroporous membranes. 

---